As US officials proclaim an alleged European terror plot still active, New York City police conducted a drill Thursday that simulated a Mumbai-style attack on civilians on a crowded street in Manhattan's financial district.
Police Commissioner Ray Kelly addressed the media before the drill, which began with two large explosions. "This is what we do," he explained. "We think the unthinkable." The drill simulated multiple bombs and shooters, including a bomb under a vehicle, and police responded with helicopters, dogs, automatic weapons and an armored car.
Earlier Thursday, the State Department's counterterror chief told reports in London that the travel alert issued last week that advised travelers in Europe to be careful was still in effect. "We don't view the conditions as warranting us rescinding the alert," said Daniel Benjamin. The alert was issued Oct. 3, when intelligence led authorities to believe a Mumbai-style assault on so-called "soft" civilian targets might be imminent in Europe.
In the immediate aftermath of the 2008 Mumbai assault that claimed 175 lives, the NYPD revised its tactics to deal with a terrorist commando assault. During Thursday's drill in the Bronx, heavily armed Emergency Service Unit officers were backed by officers from the Organized Crime Control Bureau trained to respond to such an attack. The OCCB officers are intended to beef up the NYPD response and prevent multiple simultaneous attacks from overwhelming the responding force.
The drill simulated an attack in lower Manhattan's financial district, near Wall Street and Ground Zero, on a mock block that contained a department store, a hotel and a federal regulatory agency. European authorities view these as the kind of "soft" and financial targets that might be attacked in a commando-style assault. Multiple civilians and officers were "shot" during the drill.
"We've got some info from one of the perps that the Empire State Building might be next," one police radio crackled during the drill.
As it did, helmeted cops with M4 rifles and M14 assault rifles began stalking the street hunting snipers and assailants.
"What we try to do is stress the system," Kelly explained, who said the exercise was the ninth since Mumbai. Footage of the drill will be featured on Friday's episode of "Brian Ross Investigates," which can be seen on ABC News Now or on the web.
The State Department issued its highly unusual travel advisory on Oct. 3, to "alert U.S. citizens to the potential for terrorist attacks in Europe. ... Current information suggests that al Qaeda and affiliated organizations continue to plan terrorist attacks."
While the advisory does not name potential targets, it says "U.S. citizens are reminded of the potential for terrorists to attack public transportation systems and other tourist infrastructure." It recommends that U.S. citizens "take every precaution to be aware of their surroundings" and register their travel plans on the State Department's travel registration web site.
The alert was issued because of strong concerns that terrorist teams in Europe have selected their targets and are now ready to strike at airports and tourist attractions, according to multiple law enforcement and intelligence sources.
European and U.S. authorities first learned of the plot over the summer following the capture of Ahmed Siddiqui, a suspected German terrorist who had been training in Pakistan.
Recent law enforcement operations within the United States have helped to flush out chatter that added to earlier concerns about the U.S. homeland as a possible additional target of the attacks.
Known targets are believed to include England, France and Germany. Additional European countries, including Italy and Belgium, are also targets, multiple sources say.
Siddiqui's claims about a multi-city plot against Europe have been bolstered by other "highly reliable" sources of information, US and German intelligence officials said Thursday.
Siddiqui told American interrogators at the Bagram Airfield in Afghanistan that Osama bin Laden had personally blessed the plan, officials said.
Since then, US and German officials said, Siddiqui's claims have been verified by a second captured German terror recruit and "other sources" that officials were reluctant to describe in detail for fear of compromising law enforcement operations.
"There are several different sources, all confirming that there are plots afoot by al Qaeda central, that is to say the Osama bin Laden organization in Pakistan, to do attacks in Europe," said Dick Clarke, a former White House national security official and now an ABC News consultant. "Now they don't have anything that points to the United States yet, but if there were to be simultaneous attacks in Europe, it's at least possible there would be a simultaneous attack in the United States as well."
German intelligence officials told ABCNews.com that about 45 other "potentially dangerous" individuals in Germany are being tracked as officials seek to prevent an attack from taking place.
Siddiqui worked as a cleaner at the Hamburg airport and was a "devout member" of the al-Quds mosque in Hamburg, where Mohammed Atta and other 9/11 hijackers gathered prior to their attack.
The mosque was closed after Siddiqui's arrest, based on the information he provided. Officials told ABC News that Siddiqui had been under surveillance since 1997 and left the country for Pakistan in 2009.
Officials in Germany and the United States said they still did not have a specific date of the timing of the plot, and US officials say they believe the plot's "trigger date" may have been delayed because of the media coverage and government travel alerts.
"What we've seen in the past with al Qaeda, when one of their attacks is partially exposed before it happens, they pull back, they regroup, they wait a while," said Clarke. "Sometimes they wait as much as one year. In the case of 9/11, I believe that they waited perhaps a month or two from when they originally intended to do it because of the terror alerts that we conducted back then. They know it's better not to stage these things when everyone's looking for them."